I have a 36 gal tank that im cycling right now with 5 Red Minor Tetra in it. I know they are notorious fin nippers so I made sure that I got 5 of them. Well they sometimes chase each other around the tank but it doesn't really appear that their fins are being damaged. Is this chasing that they're doing just fun or are they being aggressive? I'm really nervous about adding more fish, I don't want them killing other fish. Any suggestions? Here's a pic of the tank, should I add some more plants?